left side percentages and cross relations

B

BANDIT 518

Member
I read on another post it states The closer cross is to being equal to leftside, the tighter the kart is going to be. by Mike McCarty

Ok I can understand that

But what if your leftside is higher or lower then your cross what happens in each instance ??

I know we normally look at percentages for the cross,leftside and front
How close is close enough? If a kart calls for 60 cross is more or less ok?
If so how much more or less can you be off?

Ray
 
Remember first Cross should be looked at as more of a fine tuning % age, Vs left and nose, then 2nd Most all chassis have a dead zone on cross where 2 washers do pretty much nothing, some it may be between 58 and 62, some 60 to 63 you need to find that spot, Left and cross is more Track condition related as well, not just what is recommended, Left and nose with in .5 % isn't bad, cross 2 %, If I were off on cross I would want to be under.
 
My personal belief is the left and cross relationship is meaningless and Mike made a leap to explain something he did not understand. He's guilty of that several times.

Cross always Always ALWAYS tightens the chassis. Did I say always enough times ALWAYS? ALWAYS!!

Now you say "well I know that's not true, whenever I...." to which I say ALWAYS TIGHTENS

Then you say "But...." and I say ALWAYS!!!!

Then you get smart and say "Well how come when I...." Then finally before I set you on fire for not understanding the meaning of ALWAYS I teach you how cross works and you go "oh, well now that makes perfect sense! cross always tightens" and you live.

What you are managing with cross is the relationship between the RF and RR tires (bet you didn't realize that). In extreme low cross situations the RR is king. Lowering cross will take the LR out of the kart reducing drag and freeing the rear (pay attention this is important) of the kart up. The more cross you add the more drag you get and the tighter the rear (still paying attention yes?) becomes.

Now each time we add cross the RF gets a little stronger and the RR gets a little weaker. Eventually you get to the supposed dead zone where neither tire is strong enough to dominate the kart and cross adjustments really don't accomplish anything. But finally we reach a point where the RR just plain becomes too weak. Depending on design this is somewhere between 58 and 64%.

When we get to this point the RF takes control of the kart and the front (still paying attention) begins to overpower the rear. When this happens the kart begins to break free and "feel" loose. It's actually very VERY tight.

Now simplifying for those that were too lazy to follow:
Low cross = free rear = loose rear
high cross = tight front = loose rear
 
JWD said:
My personal belief is the left and cross relationship is meaningless and Mike made a leap to explain something he did not understand. He's guilty of that several times.

Cross always Always ALWAYS tightens the chassis. Did I say always enough times ALWAYS? ALWAYS!!

Now you say "well I know that's not true, whenever I...." to which I say ALWAYS TIGHTENS

Then you say "But...." and I say ALWAYS!!!!

Then you get smart and say "Well how come when I...." Then finally before I set you on fire for not understanding the meaning of ALWAYS I teach you how cross works and you go "oh, well now that makes perfect sense! cross always tightens" and you live.

What you are managing with cross is the relationship between the RF and RR tires (bet you didn't realize that). In extreme low cross situations the RR is king. Lowering cross will take the LR out of the kart reducing drag and freeing the rear (pay attention this is important) of the kart up. The more cross you add the more drag you get and the tighter the rear (still paying attention yes?) becomes.

Now each time we add cross the RF gets a little stronger and the RR gets a little weaker. Eventually you get to the supposed dead zone where neither tire is strong enough to dominate the kart and cross adjustments really don't accomplish anything. But finally we reach a point where the RR just plain becomes too weak. Depending on design this is somewhere between 58 and 64%.

When we get to this point the RF takes control of the kart and the front (still paying attention) begins to overpower the rear. When this happens the kart begins to break free and "feel" loose. It's actually very VERY tight.

Now simplifying for those that were too lazy to follow:
Low cross = free rear = loose rear
high cross = tight front = loose rear
Click to expand...

WOW....all I can say is THANK YOU for such an informative post.
 
In what situation do you prefer the kart to be overpowered by the rf? In what situation do you prefer the kart to be overpowered by the rr? Is the kart fastest being balanced and the cross being in the "dead zone"
 
I'm constantly changing my thoughts on stuff. Right now I see only one place to be faster and everyplace else it's about being as good as you can be. I'm also thinking it's faster to spend as much time as you can on the part of the track where you can be faster.

maybe?

and I still figure Joey is right when he says something, so for me for now it's about how to relate what he said to the only place on the track, where you can be faster. ... :)

yep, I'm confused too, not about what he wrote, but about how I want to apply it. ... :)

... When ever I think about what is fast at the limit of what you can do, I to this day still can see in my mind Chris Gabehart going through three and four at Charlotte Briggs and Straton 500. I also see it in person by some if not many, most every year at Fort Wayne, through three and four. Still amazes me and I wish I understood it. ... :(
 
... ya know, I'm able to see this in my mind in just about everything LTO I see race. Never seen a NASCAR race, but if I ever do I now know where I want to sit to watch the race. ... :)
 
GregMiller04 said:
In what situation do you prefer the kart to be overpowered by the rf? In what situation do you prefer the kart to be overpowered by the rr? Is the kart fastest being balanced and the cross being in the "dead zone"
Click to expand...

1. All situations
2. Never
3. Absolutely not!
 
edit up front: Don't anyone read what's below. It's only there so I can see how dumb it is tomorrow. ... :)

Too much RF and I see either push or loose. All depending on if you loose all rotation from the axle and what you have for a RR. I'm thinking now you can set rear rotation, to get more or less, in terms or thinking of how much you use your RF. And that may be what allows different staggers to work. nope, If I throw in how I sort of remember you presenting stagger in terms of rotation offered, it probably is stagger first as needed, and then work how much you use the RF to help what's already correct. ... just thunkin out loud. sorry.

Making it work, doesn't mean it's right as far as what's fast. ... i'm thunkin too hard, but it's fun... thanks

sure hope I'm putting my thoughts and thunkin on this, to the right part of the track. ... I think I am.
 
paulkish said:
edit up front: Don't anyone read what's below. It's only there so I can see how dumb it is tomorrow. ... :)

Too much RF and I see either push or loose. All depending on if you lose all rotation from the axle and what you have for a RR. I'm thinking now you can set rear rotation, to get more or less, in terms or thinking of how much you use your RF. it is stagger first as needed, and then work how much you use the RF to help what's already correct. ... just thunkin out loud. sorry.

Making it work, doesn't mean it's right as far as what's fast. ... i'm thunkin too hard, but it's fun... thanks

sure hope I'm putting my thoughts and thunkin on this, to the right part of the track. ... I think I am.
Click to expand...

I edited your post for you. It's right now :)
 
BANDIT 518 said:
OK so how close is close on percentages? .5? .2? 2? or is it a drive it see how it feels kinda thing?
Click to expand...

I think in this thread JWD explained there is no relationship between left, cross and a mythical dead zone.

He also clearly said your book is wrong and miss leading about it. The author made a false assumption and gave you incorrect information.
 
I understand as much as I can what JWD said. Im ok with understanding that (or trying to)
What Im asking is if I have my kart on scales and the percentages read 43 front and they call for 44 is that good enough?
Im asking is close close enough or does it have to be dead nuts on
If I have 52 left and it calls for 54 is that close enough?
Are the chassis fabricators numbers gospel or is the room for +/- ??
I know Im learning and not too sure one scaling
I hope this isn't a stupid heres your sign question

Ray
 
I think normally you want your front and left to be within .2%, maybe .5% of what you need. Cross can be off 2% or so and you would still be ok. The chassis fabricators numbers are definitely not gospel. A lot of the fastest guys in the country won't be on the factory recommended numbers. With that being said, you should try to get as close to their numbers as you can to start with, and then go from there.
 
Seems to me, if someone from your track tells you what they should be, then that's what they should be. On the other hand, someone who's never been to your track can only give you a starting point.

No matter where you set it, if it works it's right, if it doesn't it's not. And even if it works, playing around with that percentages is called learning. You change something, if it works better, you learned something. If it doesn't work, of course you've learned something else.

I would think, if you get it close, and it works, then close enough is good. If it doesn't work, just the opposite. In any case, even if it's right on, and it doesn't work, then you've got to try something else, real simple.
 
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